1. Field of the Invention
The present invention relates to a power train of automatic transmission, and more particularly to a power train of automatic transmission adapted to arrange an under drive clutch, a reverse clutch and a kickdown brake behind a planetary gear set and to provide an over drive clutch and a transfer driver gear in front of the planetary gear set.
2. Description of the Prior Art
FIG. 6 is a schematic diagram for illustrating a power train according to the prior art. The power train of automatic transmission is arranged in front of a planetary gear set 2 with a front clutch 8 connected to a reverse sun gear 6 by a first power transmission member 4, a rear clutch 14 connected to a forward sun gear 12 by a second power transmission member 10, a kickdown band brake 16 controlling a rotary power of the first power transmission member 4 and a low reverse brake 24 connected to a transmission housing 22 for controlling a one-way clutch 20 connected to a long pinion 17 and a third power transmission member 18 and is provided at a rear end thereof with a transfer drive gear 30 meshed with a transfer driven gear 28 by being connected to an annulus gear 26 and an end clutch 34 connected to a planetary carrier 32.
The transfer driven gear 28 is connected by a transfer shaft 36 and a deep drive gear 38.
FIG. 7 is a schematic diagram for illustrating a final reduction gear unit applied to a power train of automatic transmission according to the prior art.
In the final reduction gear unit 44, an input from an input shaft 40 is transmitted to a transfer drive gear 30 via planetary gear set 2, and the power transmitted thereby is transmitted to wheels via the transfer driven gear 28 meshed with the transfer shaft 36 and the deep drive gear 38.
The transfer drive gear 30 is connected to an annulus gear 26 of the planetary gear set 2 via a clocking nut 46 to be mounted at an output flange 48.
The transfer drive gear 30 is rotably supported by double angular bearing 54 fixed by a bolt 52 to the transmission housing 22. The transfer driven gear 28 meshed with the transfer drive gear 30 is also secured to the transfer shaft 36 by a locking nut 56.
FIG. 8 is a schematic diagram for illustrating an end clutch unit according to the prior art, where the end clutch unit 34 is arranged at an end clutch shaft 58 of input shaft 40 with an end clutch hub 60, at the input shaft 40 with an end clutch retainer 62, and there between with a clutch reaction plate 64, clutch plate 66 and a clutch disc 68, and includes an end clutch piston 70 disposed in front of the end clutch retainer 62 and an end clutch return spring 72 supporting the end clutch piston 70.
The end clutch unit 34 is clutched when oil pressure is applied through an oil orifice 74 provided at the end clutch retainer 62 while the end clutch piston 70 copes with the resilience of the end clutch return spring 72 to press the clutch plate 66 and clutch disc 68.
Conversely, when oil pressure applied to the end clutch unit 34 is released, the end clutch piston 70 is retracted by the end clutch return spring 72 to separate the clutch plate 66 and the clutch disc 68, thereby blocking the power transmission.
FIG. 9 is a schematic diagram for illustrating front and rear clutch intermittent controller of automatic transmission according to the prior art, where the front and rear clutch intermittent controller 80 includes at front side of the planetary gear set 2 a kickdown band brake 16, front clutch 8 and a rear clutch 14.
The kickdown band brake 16 is arranged at a peripheral surface of kickdown drum 82. The rear clutch 14 includes a clutch reaction plate 88 and a clutch disc 90 and a clutch plate 92 between rear clutch retainer 84 disposed at the input shaft 40 and rear clutch hub 86 connected to the forward sun gear 12.
Furthermore, the rear clutch 14 is also provided with a rear clutch piston 98 which copes with resilience of the rear clutch return spring 96 supported by rear clutch return spring retainer 94, advances by way of pressure of supplied oil and presses the clutch disc 90 and clutch plate 92 to interrupt the power.
Front clutch 8 includes a front clutch reaction plate 104 disposed between front clutch hub 100 formed at rear clutch retainer 84 and front clutch retainer 84, a clutch disc 106, a clutch plate 108 and a front clutch piston 112 for coping with the resilient of front clutch return spring 110 to advance by way of oil pressure.
Now, operation of rear clutch at the front and rear clutch intermittent controller 80 thus described will be described.
When pressure is applied through an oil orifice 114 formed at the rear clutch retainer 84, the rear clutch piston 98 copes with the resilience and advances to press the clutch disc 90 and the clutch plate 92 for integration and power transfer.
Furthermore, when the oil pressure is applied to the front clutch 8, the clutch disc 106 and the clutch plate 108 are integrated by the front clutch piston 112 to transfer the power to the front clutch retainer 102.
The power transferred is transmitted to the reverse sun gear 6 via the kickdown drum 82 and to transfer drive gear via the long pinion 17, annulus gear 26 and the like by way of planet carrier 118 fixed by low reverse brake 116 as repulsive element.
Now, transmission action of the power train at the automatic transmission will be described.
&lt;First speed&gt;
The rear clutch 14 as input element and one-way clutch 20 as repulsive element operate to form a first speed of drive "D" range.
The power input to the input shaft 40 is transmitted to the forward sun gear 12 via the rear clutch 14 and again transmitted to transfer drive gear 30 through short pinion 42, long pinion 17 and the annulus gear 26 with the planetary carrier 32 secured to the one-way clutch 20 as repulsive faction.
&lt;Second speed&gt;
the rear clutch 14 as input element and kickdown band brake 16 as repulsive element are operated to form a second speed of drive "D" range. The power input to the input shaft 40 is transmitted to the forward sun gear 12 via the rear clutch 14 and is again transmitted to the transfer drive gear 30 through the short pinion 42, long pinion 17 and annulus gear 26 with the reverse gear 6 secured by the kickdown band brake 16 as repulsive factor.
&lt;Third speed&gt;
The rear clutch 14 as input element and front clutch 8 as repulsive element are operated to cause the planetary gear set 2 to integrally rotate and to perform a third speed of drive "D" range.
The power input to the input shaft 40 is transmitted simultaneously to the rear clutch 14 and the front clutch 8 and the power transmitted to the rear clutch 14 is transmitted to the forward sun gear 12 and the power transmitted to the front clutch 8 is transferred to the reverse sun gear 6. At this time, the planetary gear set 2 is locked to be integrally rotated while the power therefrom is transmitted to transfer drive gear 30.
&lt;Fourth speed&gt;
The end clutch 34 as input element and kickdown band brake 16 as repulsive element are operated to form a fourth speed of drive "D" range. The power input to the input shaft 40 is transmitted to the planetary carrier 32 through end clutch 34 and is again transmitted to the transfer drive gear 30 via long pinion 17, annulus gear 26 with the reverse sun gear 6 secured by the kickdown band brake 16 as repulsive factor.
&lt;Reverse&gt;
The front clutch 8 as input element and planetary carrier 32 secured by the lower reverse brake 24 as repulsive element are operated to cause the power to be transmitted to the transfer drive gear 30 via the long pinion 27 and the annulus gear 26.